One conventionally known type of a mechanical seal is, as shown in FIG. 7, an inside-format mechanical seal in which a sealed fluid that may leak from the outer circumference of a sealing face to the inner circumference direction is sealed, wherein: an annular rotation-side sealing ring 53 provided, via a sleeve 51 and a cup gasket 52, on the side of a rotating shaft 50 for driving a pump impeller (not shown) on the high-pressure fluid-side, so as to be capable of rotating integrally with the rotating shaft 50; and an annular fixed-side sealing ring 55 provided, via a bellows 57 in a cartridge 56, to a housing 54 Document of the pump in a non-rotating state so as to be capable of axial movement, are caused by the bellows 57 and a coiled wave spring 58 axially urging the fixed-side sealing ring 55 to slide against each other in intimate contact at respective sealing faces S which have been mirror-surface-finished by lapping or the like (hereafter referred to as “prior art 1”; see, e.g., Patent Document 1). The bellows 57 in the mechanical seal in this prior art is made from rubber, and has one end attached to the fixed ring 55 via a case 59 and the other end attached to a cartridge inner cylinder part 56 via a driving band 60.
Patent Document 2 discloses an invention of a mechanical seal in which, as shown in PIG. 8, a fixed-side sealing ring 62 is attached to a housing 61, a rotation-side sealing ring 63 is provided to a shaft which is rotatably supported by the housing 61, and the fixed-side sealing ring 62 and the rotation-side sealing ring 63 are in elastic contact with each other so as to be capable of sliding, wherein a fixing claw 64a is formed on the right end of a metal bellows 64 so that the metal bellows 64 supports the fixed-side sealing ring 62 so as to be capable of axial movement, the fixing claw 64a is bent and the fixed-side sealing ring 62 is supported at the right-end interior of the metal bellows 64, and the left end of the metal bellows 64 is directly fixed to the housing 61 (hereafter referred to as “prior art 2”; see Patent Citation 2).
However, in prior art 1, the bellows 57 being made from rubber presents problems such as degradation or tearing of the bent part. Problems are also presented in that an urging member such as the coiled wave spring 58 and an attaching member such as the driving band 60 are required, increasing the number of components.
In prior art 2, since the structure is one in which the fixed ring 62 is directly supported by the metal bellows 64 and the metal bellows 64 is directly fixed to the housing 61 such that the metal bellows 64 functions also as a cartridge, a problem is presented in that the metal bellows 64 must have the same thickness as that of a cartridge or a case, resulting in an increase in the spring constant of the metal bellows 64,